Telephone-exchange system



E. H. CLARK.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION HLED OCT. 4,1918.

Patentefl Dec 112, 1922,

3 SHEETSSHEET 1.

E. H. CLARK.

TELEPHONE EXCHANGE SYSTEM.

APPLICATIQN FILED OCT. 4,19l8. 1A38f730 Patented Dean 12, 1922.

3 SHEETS-SHEET 2- Numerl'aa/ 004 6 Magi/2m E. H. CLARK.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED OCT. 4,1918- 1;,438fi7430 Patented Dec. 12, 1922., 5 3 sHEE'TssHEE13.

//7ve/7/0/ [agar/7f 6/0/74.

atented Dec. 12, 1922.

UNITED STATES PATENT OFFICE.

EDGAR H. CLARK, OF NEW YORK, N. Y., ASSIGNOR '10 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed October 4, 1918. Serial No. 256,841.

To all whom it may concern: 7 Be it known that I, EDGAR H. CLARK, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

I This invention relates to telephone sys- 10 tems employing automatic switches.

The present invention has for its purpose the provision of an improved signaling system in which indicating devices are controlled over a metallic circuit by impulses of various characteristics transmitted over said circuit.

In its more specific embodiment, the pres ent invention is employed in an automatic telephone system in which calling lines terindicated by sets of lamps, a set of lamps being provided for each digit or character of the wanted number. These lamps are selectively operated in response to the operation of a sending device which is variably controlled by the A operator.

One feature of the invention consists in the control of an indicating device by impulses varying indirection or polarity.

Another feature of the invention consists in the control of an idicating device by impulses of current of different values or strength.

These and other features of the invention will appear in the accompanying drawing and description together with the appended claims.

The drawings, with Fig. 2 placed below Fig. 1 and -with Fig. 3 placed at the right of Fig. 2, diagrammatically represent a portion of a telephone system ememploying the present invention. Fig. 1 shows a calling subscribers substation and line, with brushes of a district selector at the minating in a semi-automatic telephone ex "spirit of the invention.

A operators position, a callin plu and jack at the B operators position and trialled subscribers substation apparatus and line. Within the small dotted rectangle at the lefthand side of Fig. 1 there are shown the brushes of a cord finder switch which operate to connect an idle sending device to a cord circuit which has been connected to the calling line. Within the large dotted rectangle at the right-hand side of Fig. 1 there are shown the operators key set and the registers of the sending device for controlling the transmission of impulses to the number indicatin device. Within the dotted enclosure in t e middle of Fig. 1 there is 70 shown an impulse transmitting device, which, under the control of the registers, transmits various combinations of impulses to actuate the number indicating device. In Fig. 2 there are shown the various relays which control the lighting of the proper stations lamp, as well as the switching rela s which operate to control the actuation oft e thousands, hundreds, tens and units indicating devices-in proper sequence. Fig. 3 in its lower right-hand corner shows the lamps and controlling relays for indicating the thousands digit, at the lower left-hand corner of Fig. 3, the hundreds at thempper left-hand corner of Fig. 3, the tens; and at the upper right-hand corner of Fig. 3, the units lamps and the relays for controlling the same.

In this disclosure the showing of the apparatus and circuits for selecting the B operators position has been abbreviated, but it may be of the character of the system disclosed in the patent to Lundell, No. 1,168,319 of January 18, 1916, or it may be similar to the system shown in applicants copending application, Serial No. 178,468, filed July 3, 191

The trunk selecting-switch referred to in the description may be of the t pe illustrated in the patent to Craft and eynolds, No. 100 1,123,696 of January 5, 1915, although it will be readily understood that any autoimatic selector switch can be employed in this system without departing from the In the description reference is made to sequence switches and registers, the structure of which may be similar to that shown in the patent to Reynolds and Baldwin, No.

1,127,808 of February 9, 1915.

In general, the present system comprises a set of operators keys which control sequence switch registers, all of which are shown in the dotted rectangular at the right in Fig. 1. A device for sending impulses as determined by the sequence switch registers is shown in the upper left-hand dotted enclosure in F g. 1, and an arrangement of relays for receiving these impulses shown in Figs. 2 and 3.

In Big. 2 there are shown three relays in series, Nos. 201, 202 and 203, which respond directly to'the transmitted impulses. These relays in turn control a combination of two relays 207 and 209 which have a peculiar interaction, as will be hereinafter more fully explained. A set of relays, such as and 210, is provided for each one of the digits oi the called number and these relays are c0ntrolled through the interaction of the relays 207 and 209. p

There is provided a set ,bf indicatlng lamps for each one of the digits of the called number, each set of lamps being controlled by a set of lamp controlling relays A, B, C and D. As shown in Fig. 3, the set A, etc., controls the thousands lamps, the set A etc., controls the hundreds lamps, the set A etc., controls the tens lamps, and the set A, etc., controls the units lamps. As shown in Fig. 2 the set A, B and C controls the stations lamps.

The impulses transmitted by the device controlled by sequence switch 114 in Fig. 1 are in the nature of a code, these impulses being in a continuous train of positive and negative imapulses of light and heavy current. The impulses 0 light current are produced through a grounded battery 'cur-. rent flowing through the resistance 142 to the combination of sequence {switch contacts,

133 and 139. The impulses of heavy current, are produced by grounded battery current flowing through this same resistance 142 and the low resistance 130 in parallel, the parallel connection. being affected through the various register sequence switch contacts and sequence switch contacts con-- trolled by the switch 114 shown in an ar-. rangement above the resistance 130.- For convenience, hereafter the heavy current will be spoken of as produced by the low resistance 130, the high resistance 142 being left out of consideration since it is pennathe two headings Numerical code and Stations code. The light linesv above'the base lines represent impulses of light posi tive current; the heavy lines above the base lines represent impulses of heavy positive current; and the light and heavy lines bev low theba'se lines represent respectively imgulses of light and heavy negative current.

ach train of impulses consists'of' four such positive and negative impulses in a different combinatiomalways starting, however, with a positive impulse and ending with a negative impulse so that several of these trains may be merged into one long series of impulses.

As will hereinafter appear, the lamp controlling relays, A, B, C and D are only energized when an impulse of heavy current is transmitted and thus the codes diagrammatically shown give an indication of which lamp controlling relays will be energized. For instance, in the numerical code, the series of impulses for the digit 6 consists of, first, a heavy positive impulse, second, a heavy negative-impulse, third, 2. light positive impulse and fourth, a heavy negative impulse.' As indicated, the relays A, B and D willbe energized through this code. The stations code, since a smalle'rnumber of selections have to be made, never has a .heavy current impulse for the last impulse and therefore only three lamp controlling relays A, B and C are provided, the last light negative impulse being merely for switching purposes.

The particular; action of the relays as effected-by the sending ofthese code .im-

pulses will be more fully explained hereinafter.

It is believed that the invention will best tion as shown at 102. 'VVhen the calling sub- I scriberyremoves his receiver from its switchhook, a signal (not shown), is lighted at the Azoperators position. This operator there- .upon connects the co'rd'f circuit conductors 103 and 104 to the, call ng. line manually or .by any other suitable; means.

As I soon as the A operator has connecteda cord circuit brushes are indicated at 105 and 106 operates to connect an idle sending device-tothe-cord circuit taken for use. 7

When the A operator connects the cord circuit to the calling line she ascertains the number of the wanted subscriber and proceeds to set up[ this number on the keyboard of her-sending device.

Let us assume that the wantednumber to the calling line, a cord finder, whose four, five. six,seven, party W. The operathe stations register-109 will come to rest in position 4,- the thousands register 110 will stop in position'4, the; hundreds register 111 in positon ,5, the tens register 112 in.

position'fi, and the. units register 113 in position7." A It, will be assumed that the automatic trunk selecting switch whose brushes'are indicated by the numerals 107 and 108 has been set to select the proper trunk for connecting the calling subscriber with the B operators position at the office in which the wanted line terminates. It will also be assumed that the sequence switch associated with this trunk selecting switch has been moved into position 11.

After the sending device has been set and when the trunk selecting switch has been operated to extend the calling line to the 1B operators position at the desired ofiice, the sequence switch associated with the cord finder will be in position 7, where a circuit will be established to move the sequence switch 114 out of position 1. This circuit may be traced from grounded battery, magnet of the sequence switch 114, contact 115, contact 116 of the cord finder sequence switch to ground. With sequence switch 114 in position 2, a circuit is closed from ground, winding of relay 117, contact 118, cord finder brush 105, contact 119, trunk selector brush 108, lower armature and back contact of relay 120, winding 121 of the repeating coil, winding of relay 123, to grounded battery. Relays 117 and 123 are operated by current flowing over this circuit. At the armature and front contact of relay 117 a circuit is closed to ground, through contact 124, magnet of the sequence switch 114 to grounded battery, to move this sequence switch out of position 2 and into position 3. At the front contact and armature of relay 123 a circuit is closed from ground, through the left-hand back contact and armature of relay 125, the lamp 126, to grounded battery. Lamp 126, in lighting, indicates to the B operator that a call is waiting attention and also indicates the trunk over which the call has been extended. The B operator thereupon depresses key 127 to associate a number indicating device with the trunk over which the call has been extended.

Upon the depression of key 127 a circuit is closed from ground, winding of relay 120, contact of key 127, conductor 128, winding of relay 200 to grounded battery. Relay 200 attracts its armatures to apply ground to the various controlling leads of the number indicating device. At the same time the relay 120 attracts its armatures, and at its lower armature and back contact interrupts the energizing circuit of relay 117. When this relay deenergizes it closes a circuit from ground, its armature and back contact, contact 129, magnet of sequence switch 114 to grounded battery, to move sequence switch 114 out of position 3 and through its various operating positions back to position 1, during which a complete set of code impulses is transmitted to the relays 201, 202 and 203.

When sequence switch 114 moves into position 4 a circuit is closed from grounded battery through the low resistance 130, contacts 131, 132 and 133, cord finder brush 105 and contact 119, trunk selector brush 108, lower armature and front contact of relay 120, conductor 134, winding of the positive polarized relay 201, winding of the negative polarized relay 202, winding of the marginal relay 203, conductor 204, upper front contact and armature of relay 120, trunk selector brush 107, contact 135, cord finder brush 106, contact 136 to ground. Since the impulse circuit extends through the low resistance 130 the marginal relay 203 is energized, and since this impulse is positive, the relay 201 also attracts its armature. With these two relays energized the stations relay A is actuated over a circuit closed from grounded battery, left-hand winding of the relay A, conductor 205, lefthand armature and back contact of relay 206, left-hand back contact and armature of relay 207, left-hand front contact and armature of relay 203, right-hand front contact andarmature of relay 201, conductor 208, to ground at the armature of relay 200. Relay A is energized and at its righthand front contact and armature completes 'a locking circuit for itself from grounded battery, through both its windings in series, to round over conductor 208.

11 position 4%- of sequence switch 114 a current impulse of the opposite polarity is transmitted from grounded battery, low resistance 130, contacts 137, 138, 139, cord finder brush 106, contact 135, trunk selector brush 107, upper armature and front contact of relay 120, conductor 204, winding of marginal relay 203, winding of the negative polarized relay 202, positive polarized relay 201, conductor 134, lower front contact and armature of relay 120, trunk selector brush 108, contact 119, cord finder brush 105, contact 140 to ground. In response to this impulse the relays 202 and 203 are energized and attract their armatures.

The peculiar action and interactions of the relays 207 and 209 should be noted at this point. Relay 209 has two windings, the left one being marginal and used as a holding winding after the armatures have been attracted by the energization of, the right winding. When ground is first placed on the left armature of relay 209 relay 207 is energized in series with the left winding of 209, but this left winding of relay 209 placed on the left-hand armature of relay 209 the winding of relay 207 and the right. hand winding of relay 209 are short-circulted and relay 207 becomes deenerglzed but relay 209 remains energized through its lefthand marginal holding winding. When finally the ground on the left-hand arma ture of relay 209 is removed relay 209 becomes deenergized.

Thus, through two successive appllcations and removals of ground on the lefthand armature of relay 209 we have, first, an actuation of relay 207, second, an actuation of relay 209, third, a deenergization of relay 207 and fourth, a deenergization of relay 209. 4

Going back now to the point where relays 202 and 203 were energized it will be noted that as soon as relay 202 attracted its armature it closed a circuit from grounded battery, left-hand winding of relay 209, winding of relay 207, left-hand back contact and armature of relay 209, front contact and armature of relay 202 to ground over conductor 208. The left-hand winding of relay 209 is a holding winding and operates to hold the armatures of this relay attracted when once they have been actuatedby the right-hand or pull-up winding of this relay. Thus the relay 209 does not attract its armatures, but the relay 207 does attract its armatures in this circuit. At the inner right-hand front contact and armature of this relay a break-point in the energizing circuit of right-hand winding of relay 209, is closed, but this winding is shortcircuited at this time.

At the outer right-hand front contact and armature of relay 207, an energizing circuit for relay 206 is completed from grounded battery, winding of this relay, inner lefthand backcontact and armature of relay 210, through the armature of relay 207 to ground over conductor 208. Relayv 206 attracts its armatures and at its inner righthand front contact and armature closes an energizing circuit for the relay 210, but

since this last mentioned relay is short-circuited at this time, it does not attract its armatures.

Also in response to the actuation of relays 202 and 203 the stations relay B is energized over a circuit from grounded battery, left-hand winding of relay B, right-hand back contact and armature of relay 210, outer right-hand back contact and armature of relay 209, right-hand front contact and armature of relay 203, front contact and armature of relay 202 to ground over conductor 208.v The relay 'B attracts its armatures and at its right-hand front contact and armature completes a locking circuit for itself.

When the sequence switch 114 moves into position 5 a heavy positive eurrentimpulse lay is transmitted from grounded battery, low

resistance 130, contacts 172, 141 and 133, over the circuit previously described to ground through contact 136. In response to this heavy positive current impulse the relays 201 and 203 attract their armatures. At this time, however, the relay 202 becomes inert, so that the short circuit about the right-hand winding of relay 209 is removed and a circuit is completed from grounded battery, through the left-hand winding of relay 209, winding of relay 207, right-hand Winding of relay 209, inner right-hand front contact and armature of relay 207 to ground over conductor 208. Since the right-hand Winding of relay 209 is energized, this relay now attracts its armatures.

In response to this last impulse of heavy positive current the relay C is also energized over a circuit traceable from grounded battery, left-hand winding of relay C, outer right-hand back contact and armature of relay 211, outer right-hand front contact and armature of relay 206, left-hand front contact and armature of relay 207, left-hand front contact and armature of relay 203, contact and armature of relay 201 to ground over conductor 208. Relay C attracts its armatures and through its right-hand armature and front contact completes a locking circuit for itself. As soon as the relay 209 attracts its armatures the relay 210, which had previously been shunted, is energized over a circuit extending from grounded battery, winding of relays 206 and 210, inner right-hand front contact and armature of relay 206, conductor 208, to ground.

In position 51} of sequence switch 114 a weak negative impulse is transmitted from grounded battery through high resistance 142, contact 139, over the circuit previously described to ground through contact 140. In response to this negative impulse the relay 202 only attracts its armature and thereby completes a holding circuit for the, re-

209 from grounded battery, left-hand winding of relay 209, left-hand contact and armature of this relay, contact and armature of relay 202, conductor 208, to ground. The relay 207 is short-circuited and retracts its armatures. This completes the selection of the stations lamp controllingrelays.

Since the thousands register 110 has been set in position 4, when the sequence switch 114 is moved into position 6 no heavy current impulse is transmitted but a light impulse is sent from grounded battery, through high resistance 142, contact 133, over the circuit previously described to ground through contact 136. In response to this impulse the relay 202 deenergizes to cause the release of the relay 209. At this time the relay 201 energizes, but since the marginal relay 203 is not also energized, its actuation is of no avail.

In position 6% of sequence switch 114 a strong negative impulse is transmitted from grounded battery, through the low resistance 130, contacts 143, 144 and 139, over the circuit previously described to ground through contact 140. In response to this impulse the relays 202 and 203 are energized and complete a circuit from grounded battery, left-hand winding of relay B (Fig. 4), conductor 300, inner right-hand back contact and armature of relay 213, righthand front contact and armature of relay 210, outer right-hand contact and armature of relay 209, right-hand front contacts and armatures of relays 203 and 202 to ground over conductor 208. Relay B" attracts its armatures and completes a locking circuit for itself from grounded battery, through both of its windin s in series, its right-hand front contact an armature, conductor 301, inner left-hand front contact and armature of relay 200 to ground. In response to the energization of relay 202 the relay 207 i again energized over a circuit extending from grounded battery, left-hand back contact and armature of relay 209, front contact and armature of relay 202 to ground over conductor 208. Relay 207 attracts its armatures to prepare at its inner right-hand front contact and armature an energizing circuit for the relay 209, and at its outer right-hand front contact and armature completes an energizing circuit for the relay 211 from grounded battery, winding of this relay, inner left-.handi back contact and arma ture of relay 213, inner left front contact and armature of relay 210, outer right-hand contact and armature of relay 207 to ground over conductor 208.

With the sequence switch 114 in position 7 only a weak positive impulse is sent since the register contact 145 is not closed in position 4. In response to the weak positive impulse only the relay 201 is energized. The relay 202 deenergizes and the righthand winding of relay 209 is no longer shunted but is energized over a circuit traceable through grounded battery. lefthand winding of relay 209, winding of relay 207, right-hand winding of relay 209, inner right-hand front contact and armature of relay 207, conductor 208 to ground. Since this impulse is weak, none of the thousand lamp controlling relays are now actuated.

With the sequence switch 114 in position 71, a heavy negative impulse is transmitted from grounded battery, through the low resistance 130, contacts 146, 147 and 139, over the circuit previously described, to ground through contact 140. In response to this impulse relays 202 and 20 are energized, and relay 202 complete a holding circuit for relay 209 from grounded battery, 1efthand.winding and front contact and armature of relay 209, the front contact and armature of relay 202 to ground over conductor 208. The relay 207 is thereby shunted and retracts its armatures. In response to the operation of relays 202 and 203 an energizing circuit is completed for relay D from grounded battery, lefthand winding of this relay conductor 302, outer right-hand back contact and armature of relay 213, outer left-hand front contact and armature of relay 210, outer righthand front contact and armature of relay 209, right-hand front contact and armature of relay 203, right-hand front contact and armature of relay 202 to ground over conductor 208. Relay D attracts its armatures and complete a locking circuit for itself over conductor 301. This completes the selection of the thousands lamp controlling relays.

Remembering now that the hundreds register 111 is set in position 5, it will be seen that in position 8 of sequence switch 114, a weak positive impulse is transmitted from grounded battery, through high resistance 142, contact 133, over the circuit previously 'described to ground through contact 136. In response to this impulse the relay 202 retracts its armature to effect the deenergization of the relay 209. The relay 209 retracts its armatures and the relay 213, previously shunted, i actuated over the circuit traceable from grounded battery, winding of relay 211. winding of relay 213, inner right-hand front contact and armature of relay 211, conductor 208 to ground' Since the marginal relay 203 is not energized, none of the hundreds lamp controlling relays are actuated.

In position 8% of sequence switch 114, however, a heavy negative impulse is transmitted from grounded battery, low resistance 130, contacts 148, 173 and 139, over the circuit previously described to ground through contact 140. In response to this heavy negative impulse relays 202 and 203 are energized. Relay 207 is again energized over a circuit traceable from grounded battery, left-hand winding of relay 209, Winding of relay 207, left-hand back contact and armature of relay 209, front contact and armature of relay 202, conductor 208, to ground. As soon as relay 207 attracts its armatures, relay 214 is energized over a circuit from grounded battery, winding of relay 214, inner left-hand back contact and armature of relay 215, inner left-hand front contact and armature of relay 213, inner left-hand front contact and armature of relay 210, outer right-hand front contact and armature of relay 207, to ground over conductor 208, Simultaneously with the relay,- conductor 303, innerQright-hand-Fback 7 contact, and' im l i relay 215 inner rh d frgntvj nta t Sand. armature of relay ,213, might-ha d frontf' contact"- and armatureof'relay 210,-router: right-hand back- I J contac't and armatufre-of frelay." 209,1, front 1 202, to ground over conductor. 208. Belay contacts; and" jarina'tures "of "relays 203 and B? attracts [its 'a rxn'at'ures; and at'iitsright- :f. 7 y I a locking'cir hand front contact andarmature completes cuit for itself a 'ver the conductor 1301 Q With the sequence switch 114-,inposition 9- only a Jweak positive impulse, is transmitted', J since the register contact 1 149 is not 1 closed 1 in"? position a 5. response ftofthis weak positive impulse the relay 201; is energiz'ed' andthe relays 5 i and 1203. deener g1ze;- The energizat'io'n of-frelay" 1201" however is 'ineflectiv'e si'nc'efthe marginal relay 203 is'inert, and none of-th-e; hundreds lamp this impulse.

controlling relays actuated in response to r I Whenthe' ,relay; 202: is deenergized the relay. 209 is operated over a circuit extending from grounded battery,'

left-hand winding of relay 209, Winding of relay 207 ,right-hand winding of relay 209,

inner right-hand front; contact" and armature of relay 207 to ground, over conductor Since contact 150 of the hundreds register 111 is not closedin position 5, only aiweak negative impulse is 1;. transmitted g-when sequence switch 114is moving through-position 9%. In response tothis negative mpulse, relay 207 is *short-circuited by .the

cuit is completed for'the relay- 209 from. 1 grounded battery, left-hand winding'of, this frelay, left-hand front contact; and armature of this relay,fright-'hand front contact and armature of relay'f202 to ground. over conductor 208. This completes theiselection I of the hundreds lamp-controlling.relays; v

It will now be noted th'atith'e-tens sequence switch register 112 is'set in positionlG',

sequence switch1114 in position 10,:j1a heavy impulse is fftra'n'smittedf E from f the selection of any one of the tens lamp [:positive actuation of relay 202 and a holding'cira grounded battery," through-flow, '{tresis t'ance 130, contacts 151, 152 a d '133;=aver =the. 611:-

a cuit previously 'described,"to ground through .contact136." In res onse'to'the heavy posi-v tive -irnpulse- 'the re ay"'202 Ideenergizes and I eifects'the deenergization' of, relay. 209.KRe-' lays-201 and 203, however, arey act-uated to complete an energizing circuit ,for :the tens f lamp;. controlling rel y c ndu 3 1 outer right-hand contact and armature' jof 7 relay 2 1- v middle right-.handfront contact -;and armature. of relay-214;,left-hand front (1,20

lay 207, left-hand front contact and armature of relay 203, right-hand front contact and armature of relay'20l, to ground over conductor 208. Relay' A attracts its armatures andat its inner right-hand front contact and armature completesa locking circuit forv itself over conductor 301.

With the sequence switch 114 in position 10% a, heavy negative impulse is transmitted .from'grounded battery, low resistance 130,

contacts153, 1541' and.'139,,over the circuit previously described to ground through contact-1 10. In response to this heavy negative impulse relays 202, 203 attract their armatures. Relay 207 is energized in a manner previously described and attracts its armaturesto complete a circuit. for the relay '217, from grounded battery, winding of this relay, inner left-hand back contact and armature of relay 218, inner left-hand front contacts and armatures of relays 215, 213

and 210, outer right-hand front contact and armature of relay 207- togroundover conductor 208. In response to the energization of relays 202, 203, the relay B is actuated cover a circuit completed from grounded battery, left-hand winding of this relay, conductor 305, inner right-hand back contact and armature of relay 218, inner right-hand front contact and armature of relay 215, inner right-hand front contact and armature of relay 213, right-hand front contact and armature of relay 210, outer right-hand back contact and armature of relay 209, righthand front contacts and armatures of relays 203 and 202 to ground over conductor 208. Relay B completes a locking circuit for itself from grounded battery, its two windings in series, itsright-hand front contact and armature to conductor 301.

vWith sequence switch 114 in position 11 a weak positive impulse is transmitted from grounded battery, resistance M2, contact 133 over the circuit previously traced to 'ground at contact 136. This results in the deenergization of relays 202 and 208 and the energization of relay 201. The deenergiza- "tion of relay 202 results as previously described, in the energization of relay 209. Since relay 203 is not energized at this time theenergizatio'n of 201 does not result in 1 controlling relays.

In position 11% of sequence switch 1141 a heavy negative current impulse is trans- .mitted from grounded battery, resistance 130, sequence switch contacts 155,156 and l39jover the'circuit previously traced back to ground at sequence switch contact 140.

This results in the deenergization of relay 201and the energization of relays 202 and battery, the left-hand winding of relay D conductor 306, the outer right-hand armature and back contact of relay 218, the outer left-hand front contact and armature of relays 215, 213 and 210, outer right-hand front contact and armature of relay 209, right-hand front contact and armature of relays 203 and 202 to ground over conductor 208. Relay ll) attracts its armatures and completes a locking circuit for itself over conductor 301 to ground. This completes the selection of the tens lamp controlling relays.

It will now be noted that the units sequence switch register 113 has been set in position 7. When the sequence switch 114 is rotated through position 12 a heavy impulse of positive current is transmitted from grounded battery, low resistance 130, contacts 157, 158, 133, over the circuit previously described to ground through contact 136. In response to this impulse, relay 202 deenergizes to effect the deenergization of the relay 209 and the relays 201 and 203 attract their armatures. The deenergization of relay 209 results in the removal of the short circuit about relay 218 and it thereupon energizes. The units lamp controlling relay A is now energized over a circuit extending from grounded battery, left-hand winding of this relay, conductor 307, middle right-hand front contacts and armatures of relays 217 and 214, left-hand front contact and armature of relays 211 and 206, left-hand back contact and armature of relay 207, left-hand front contact and armature of relay 203, right-hand front contact and armature of relay 201 to ground over conductor 208. Relay A attracts its armatures and at its inner front contact and armature closes a locking circuit for itself over conductor 301.'

In posit-ion 12:} of sequence switch 114, a heavy impulse of negative current is transmitted from grounded battery, low resistance 130, contacts 159, 160 and 139, over the circuit previously described to ground through contact 140. In response to this impulse the relays 202 and 203 attract their armatures. At the right-hand front contact and armature of relay 202 an energizing circuit is closed for the relay 207. Upon the actuation of the relay 207, a circuit is closed for the relay 219 from grounded battery, winding of this relay, the inner lefthand armatures and front contacts of relays 221, 218, 215, 213 and 210, outer front contact and armature of relay 207 to ground over conductor 208. In response to this last-mentioned impulse the relay B is also operated over a circuit traceable from grounded battery, left-hand winding of this relay, conductor 308, inner right-hand front contacts and armatures of relays 218, 215, 213, right-hand front Contact and armature tive current is transmitted over the signaling circuit. In response to this impulse the relay 202 deenergizes' and relay 201 is energized. When the relay 202 deenergizes the relays 207 and 209 again become energized in a series circuit which has previously been described. The actuation of relay 201 however does not effect the operation of any of the units lamp controlling relays since the marginal relay 203 is not operated at this time.

In position 139; of sequence switch 114 a weak impulse of negative current is transmitted over the signaling circuit. Relay 202 in response to this impulse attracts its armatures to complete a circuit through the holding winding of relay 209 and shortcircuits the relay 207. Since the marginal relay 203 is not operated the relay D is not actuated.

As sequence switch 114 passes out of position 131}- the signaling circuit is opened and all three of the relays 201, 202 and 203 be come deenergized. In response to the retraction of the armature of relay 202, relay 209 becomes deenergized and at its inner right-hand armature and contact opens the short circuit about the relay 221, which thereupon becomes energized in series with the relay 219 through the inner right-hand armature and front contact thereof.

l/Vhen the relay 217 operated it closed a circuit from ground through its left-hand front contact and armature, conductor 222, Winding of relay 310 to grounded battery. This last-mentioned relay attracts its armatures to connect battery to the various relays which control the lighting of the thousands and hundreds digit lamps. Whenrelay 221 attracted its armatures, at its outer left-hand armature and front contact it completed a circuit for energizing relay 223. to light the stations indicating lamp. At the outer right-hand armature and front contact of relay 221, a circuit is closed for lighting the selected units indicating lamps, and at the outer right-hand armature and front contact of relay 219 a circuit is closed for lighting the selected tens indicating lamps.

It will be remembered that the thousands digit lamp is No. 4 and that the relays B and D have been actuated and locked up. When the relay 310 attracts its armatures a circuit is closed from grounded battery. outer right-hand armature and contact of the relay 310, through the number 4 lamp,

right-hand armature and front contact of,

relay A, left-hand armature and front contact of relay B to the ground on the outer right-hand armature of relay 223.

It will be understood that as soon as the impulse transmitting device 114. has com-.

pleted its operation the cord finder, whose brushes are designated by the characters 105 and 106, as well as the associated sequence switch, is restored to normal. At the same I time a sequence switch, only certain of the contacts of which are shown associated with a trunk selecting switch, is moved outof position 11 to open the contacts 119 and 135 and to close the contacts 164 and 165. The B operator upon noting the number of the wanted line inserts the plug 161 into a jack 162 of this line and depresses the proper ringing key 163 for applying suitable-current to the calling line to ring the station which appears on this line.

The B operator releases the key 127 and.

effects the deenergization of relays-120 and 200. When relay 200 retracts its armatur'esl the operated relays controlling the number indicating device appearing on Figs. 2 and 3 are deenergized through the removal of ground from conductors 208 and 301 and the number indicating device is placed in condition to indicate a second wanted number.

The insertion of the plug 161 into jack 162 completes a circuit for relay 125 which upon energization causes the lighting of lamp 126 through a circuit-from grounded battery, lamp 126, armature and front contact of relay 125, armature and back contact of relay 123 to ground. I i

On retraction of the armatures of relay 120 a circuit is closed from grounded bat tery, winding of relay 123, winding 121 of the repeating coil, lower back contact and armature of relays 120, trunk selector brush 108, contact 164, conductor 104, through the calling substation apparatus 101, conductor.

103, contact 165, trunk selector brush. 107, upper armature and back contact of relay 120, winding 166 of the repeating coil, wind ing of relay 167 to ground. Relays 167 and .123 are energized in this'circuit and the movement of the armature of relay 123 causes the extinguishing of lamp 126 which thereby indicates to the B operator that the a signal calling subscriber is properly connected to the selected trunk.

At the close of the conversation, when the callin subscriber hangs up his receiver, %not shown) is operated at the A operators position and this operator proceedsto release the trunk selecting switch and other selector switches employed in the connection. When these switches are re leased the circuit for the relays 123 and 167 is opened and the lamp126 is lighted to inform the B operator that the call has terminated. This operator then removes plug 161 from jack 162.

It will thus be seen that the invention as employed in a telephone system comprises a series of number indicating lamps, one series of lamps for each character of the largest number to be indicated. These series of lamps are selectively controlled by sets of relays A B C D A B C D etc., each of these sets of relays being variably operated in succession by impulses of current transmitted over a metallic signaling circuit comprising two sides of the trunk circuit in series, and the conductors 134 and 204. The impulse sending device which transmits impulses over the metallic signaling circuit consists of a sequence switch 114 and the contacts of the various operator controlled registers designated ST, TH, H, a

T and U. The mentioned means for operating the sets of lamp relays in succession consists of a series of switching relays 210, 213', 215, 218 and 221. These switching re- Qlays. as well as the lamp controllingrelays arevariably operated in response to impulses from the transmitting device.

It will be noted that a continuous series. of weak positive impulses and weak negative lmpulses would have been produced if none of the sequence switch register contacts had been closed through the agency ofthe high resistance 142 and the combination of sequence switch contacts 133, ,136, 139 and operation of relays 206, 210, 211,213, 214,,

215, 217, 218, 219 and 221. Hence the series of weak impulses control the sequence of operation of the digits indicators.

, The impulses of heavy current are, through the agency of the low resistance 130' and the various sequence switch cams of the registers, superimposed on the impulses of light current. The function of the impulses of heavy current is, as. has been seen from the previous description, to control the energization of the lamp controlling relays so that there is present a means for sending one series of impulses to control the sequence of operation of the indicators-- dicating arrangements in automatic telephone systems or even' to telephone systems broadly.

What is claimed is:

1. In a telephone exchange system, an

operators position, an indicating device thereat, a trunk line comprising talking conductors extending to said position, means to selectively operate said indicating device by impulses of current differing in polarity a variably operable register and or impressin impulses upon the talking conductors 0 said trunk lineto control -said indicating device in accordance with the setting of said register.

2. In a signaling system, an indicating device comprising several indicators each arranged to be variably operated, a switching means comprising relays for controlling the sequence of operation of said indicators, a signaling circuit over which said indicators are controlled, and means for impressing impulses thereon of certain characteristics to control said switching means and for impressing impulses of other characteristics to operate said indicators.

3. In a signaling system, an indicatinlg device comprising several indicators eac arranged to be selectively operated, means including a train of relays operated in response to positive and negative impulses for controlling the sequence '-of: operation of said indicators, a signaling circuit over which saidindicating device and switching means are controlled, and means for transmitt'ing current impulses of the proper characteristics over such circuit to control said indicating device and switching means.

4. In a telephone system, an operators position provided with an, indicating device, a second operators position, a trunk line means interconnecting said positions, an impulse sending device at said second position for transmitting current impulses of different polarity over the two conductors of said trunk line in series to control said indicating device.

5. In a telephone system, an operators position provided with an indicating device, a second operators position, a trunk line interconnecting said positions, and an impulse sending device at said second position for transmitting impulses of various strength and polarity over said trunk line to control said indicating device.

6. In a telephone system, a telephone line, an impulse transmitting dev1ce-connectable to said line for transmitting impulses of positive and negative polarity thereover and a number indicating device controlled by impulses transmitted from said sender over two sides of said line in series.

7. In a telephone exchange system, a sending device, a plurality of variably adjustable registering devices included in said sending device, a line, an impulse transmitting device connectable to said line for transmitting impulses of varying strength thereover in accordance with the positions assumed by said registering devices, and a number indi cating device controlled by impulses transmitted from said transmitting device over the two sides of said line in series.

8. In a telephone system, a number indicating device, a signaling circuit over which impulses are transmitted to control said indicating device, an impulse sender of the sequence switch type for transmitting impulses varying in strength over said circuit, and manually controlled registers for variably controlling the operation of said impulse sender.

9. In a telephone system, a number indicating device comprising a set of lamps and lamp controlling relays for each character of the largest number to be indicated, said relays being variably controlled in response associated with said circuit for generating said impulses 10. In a signaling system, the arrangement of two relays and a circuit arrangement including a contact point whereby two successive closures and openings of said contact point will cause said relays to be successively actuated in all possible combinations.

11. In a signaling system, the arrangement of two relays and a circuit therefor including a contact point whereby successive closures and openings of said contact point will cause said relays to interc'ontrol one another in such manner that said relays are periodically actuated in various combinations substantially as described.

12. In a signaling system, the arrangement of a relay with a singlewinding, a refirst relay to be deenergized, and a subsequent opening of said contact point will cause sald second relay to be deenergized.

14. In a signaling system, the arrangement of a relay with a single Winding, a relay with a plurality of windings, and a circuit arrangement therefor including a contact point whereby the closure of said con- 1.4as,74a

15 In a signaling system, the arran ement of two relays, one being provided with a single winding and the other With a plurality of windings, and a circuit arrangement including a contact point whereby successive closures and openings of said contact point will cause, first, the energization of said single winding relay, second, the energization of said double winding relay, third, the deenergization of said single Winding relay, and fourth, the deenergization of said double winding relay.

In witness whereof, I hereunto subscribe my name this 24th day of September A. D., 1918.

EDGAR H. CLARK. 

